package com.tool.utils.utils;

import java.io.UnsupportedEncodingException;

import Decoder.BASE64Decoder;
import Decoder.BASE64Encoder;

public class Base64Utils {
	private static char[] Base64Code = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
			'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k',
			'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', '+', '/' };

	private static byte[] Base64Decode = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
			-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, 63,
			-1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, 0, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
			11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31,
			32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };

	public static String encode(byte[] b) {
		int code = 0;
		if (b == null)
			return null;
		StringBuffer sb = new StringBuffer((b.length - 1) / 3 << 6);
		for (int i = 0; i < b.length; i++) {
			code |= b[i] << 16 - i % 3 * 8 & 255 << 16 - i % 3 * 8;
			if ((i % 3 != 2) && (i != b.length - 1))
				continue;
			sb.append(Base64Code[((code & 0xFC0000) >>> 18)]);
			sb.append(Base64Code[((code & 0x3F000) >>> 12)]);
			sb.append(Base64Code[((code & 0xFC0) >>> 6)]);
			sb.append(Base64Code[(code & 0x3F)]);
			code = 0;
		}

		if (b.length % 3 > 0)
			sb.setCharAt(sb.length() - 1, '=');
		if (b.length % 3 == 1)
			sb.setCharAt(sb.length() - 2, '=');
		return sb.toString();
	}

	public static byte[] decode(String code) {
		if (code == null)
			return null;
		int len = code.length();
		if (len % 4 != 0)
			throw new IllegalArgumentException("Base64 string length must be 4*n");
		if (code.length() == 0)
			return new byte[0];
		int pad = 0;
		if (code.charAt(len - 1) == '=')
			pad++;
		if (code.charAt(len - 2) == '=')
			pad++;
		int retLen = len / 4 * 3 - pad;
		byte[] ret = new byte[retLen];
		for (int i = 0; i < len; i += 4) {
			int j = i / 4 * 3;
			char ch1 = code.charAt(i);
			char ch2 = code.charAt(i + 1);
			char ch3 = code.charAt(i + 2);
			char ch4 = code.charAt(i + 3);
			int tmp = Base64Decode[ch1] << 18 | Base64Decode[ch2] << 12 | Base64Decode[ch3] << 6 | Base64Decode[ch4];
			ret[j] = (byte) ((tmp & 0xFF0000) >> 16);
			if (i < len - 4) {
				ret[(j + 1)] = (byte) ((tmp & 0xFF00) >> 8);
				ret[(j + 2)] = (byte) (tmp & 0xFF);
			} else {
				if (j + 1 < retLen)
					ret[(j + 1)] = (byte) ((tmp & 0xFF00) >> 8);
				if (j + 2 < retLen)
					ret[(j + 2)] = (byte) (tmp & 0xFF);
			}
		}
		return ret;
	}

	// 加密
	public static String getBase64(String str) {
		byte[] b = null;
		String s = null;
		try {
			b = str.getBytes("utf-8");
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		if (b != null) {
			s = new BASE64Encoder().encode(b);
		}
		return s;
	}

	// 解密
	public static String getFromBase64(String s) {
		byte[] b = null;
		String result = null;
		if (s != null) {
			BASE64Decoder decoder = new BASE64Decoder();
			try {
				b = decoder.decodeBuffer(s);
				result = new String(b, "utf-8");
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
		return result;
	}
}
